TACOMA, Wash. (CBS/AP) Four suspects are charged in a fatal home-invasion robbery linked to a Craigslist ad, according to Washington State officials.

James Sanders, of the Pierce County community of Edgewood, Wash., was fatally shot on April 28 trying to defend his home from robbers who showed up on the pretext of purchasing a diamond ring he had advertised on the online classified site.

Sanders' wife, Charlene, told reporters last week how the people who pretended to be interested in buying a ring, robbed
and beat her family and shot her husband.

"I had a gun to the back of my head with a countdown - three, two -
and I'm just screaming and my kids are standing there, and I'm saying,
please, God, don't let them kill me, don't let them kill my kids," she
said.

She said her husband was shot trying to protect her 14-year-old son
who was being pistol-whipped. James Sanders died in his wife's arms.

"I just kept saying 'honey please stay with me, stay with me, stay
with us, don't go, don't go,' and he was just barely gasping for air,"
she said. "They took the love of my live."

Three of the suspects Kiyoshi A. Higashi, 22, and Joshua N. Reese, 20, both of Tacoma, along with Amanda C. Knight, 21, of Sumner, were arrested on May 1 during a traffic stop in California.

Officials say the fourth suspect, Clabon Berniard, 23, turned himself in to authorities on Thursday after being sought on a nationwide arrest warrant.

Investigators say they believe the people responsible for Sanders' death are also responsible for an April 25 robbery at a Lake Stevens home, north of Seattle, where the family had offered a TV for sale on Craigslist.

All four suspects are charged with first-degree murder, robbery and assault.

Knight appeared Wednesday in Pierce County Superior Court in tears and pleaded not guilty to all charges and was ordered held on $2 million bail.

Charlene Sanders was in court for Knight's appearance and called the whole experience "a nightmare" and told KOMO-TV, "When I saw her I started to shake."

She said earlier her 14-year-old son is recovering and both he and her 10-year-old son miss their father.